Electronic article surveillance (EAS) systems are used to control inventory and to prevent theft or unauthorized removal from a controlled area of items tagged with EAS security labels. Such systems may include a transmitter and a receiver to establish a surveillance zone (typically entrances and/or exits in retail stores) encompassing the controlled area. The surveillance zone is set-up such that items removed from or brought into the controlled area must traverse the surveillance zone.
An EAS security label may be affixed to an item, such as, for example, an article of merchandise, product, case, pallet, container, and the like. The label includes a marker or sensor adapted to interact with a first signal that the EAS system transmitter transmits into the surveillance zone. The interaction establishes a second signal in the surveillance zone. The EAS system receiver receives the second signal. If an item tagged with an EAS security label traverses the surveillance zone, the EAS system recognizes the second signal as an unauthorized presence of the item in the controlled area and may activate an alarm under certain circumstances, for example. Once an item is purchased, the EAS security label is deactivated so that the alarm is not activated when the label traverses the surveillance zone.